1. Field
The present invention relates to a system and method for streaming numerous video on demand (VOD) streams over a network, such as a local area, medium-sized network on a vehicle, such as an aircraft. More particularly, the present invention relates to a system and method that provides redundant and restricted paths for streaming numerous VOD streams while providing maximum bandwidth for traffic from multiple sources with minimal packet loss due to contention.
2. Description of the Related Art
In certain networks, such as those for providing VOD streams to video display devices, it can be desirable for the network to have redundant paths from the VOD sources to each video display device. By configuring the network in this manner, if the original path from the VOD source to the video display device fails, the redundant path can be used to continue to provide the VOD stream to the video display device without the viewer experiencing any significant interruption in viewing the video.
As can be appreciated by one skilled in the art, one technique for providing network redundancy employs a “spanning tree,” such as that defined in IEEE Standards 802.1D-2004 and 802.1w. This type of spanning tree provides a loop-free path when multiple paths exist in a switched or bridged Ethernet network. However, spanning trees of this nature provide no method for controlling the traffic across the established links, and only provide a single link between switches. Also, even though a spanning tree provides a loop-free path with backup, it does not handle problems that can occur due to a loss of a server.
In addition, although spanning trees are intended to be transparent to the hosts on the network, during video streaming, the clients (e.g., video display devices) very rarely send traffic to the server once they have started receiving video streams. Therefore, if the network has a failure and a new network path is created via the spanning tree, the switches in the new path are not automatically updated with the client Ethernet addresses. Hence, the switches become flooded with streams destined for clients that need to receive their streams via the new path. The streams will continue to flood the switches until the clients communicate to the server via the new network path, and the server updates the switches with the port or ports to which the clients' address need to be registered.
One way to mitigate this flooding problem would be to statically assign the Ethernet addresses to the switches. However, this is a very cumbersome and data intensive operation that requires special software to implement and validate its correctness, and does not scale well to large networks. Another way is for the clients to acknowledge each packet, or send periodic heartbeat messages to the servers. Although clients can use transmission control protocol (TCP) to acknowledge each packet, sending video via TCP creates substantial overhead on the servers and network, and would require special software, while also not scaling well and creating additional traffic to the servers that would limit the number of streams the servers could send in a large network. Alternatively, routers can be employed instead of switches, but routers are more expensive and require additional space and power which are both very limited in certain settings, such as on an airplane or other vehicle.